JP7193118B2 - heating cooker - Google Patents

Description

The present invention relates to a heat cooker.

Patent Literature 1 below describes a heat pipe type heating cooker. This heating cooker has a double-walled structure with a closed space inside, and a working fluid is injected into the closed space. Then, when the bottom portion of the heating cooker is heated, the working fluid boils, and vapor vaporized in the working fluid rises to the sides of the sealed space. As a result, the side walls inside the heating cooker are heated by the steam. Furthermore, the steam that has heated the side walls condenses and turns into a liquid as the working fluid. The hydraulic fluid that has changed to liquid descends by its own weight and returns to the bottom of the closed space. The heating cooker is heated by repeating the phase change cycle in the working fluid.

Japanese Patent No. 2713008

However, the above heat cooker has room for improvement in the following points. That is, in the heating cooker described above, the amount of working fluid in the closed space for efficiently heating the side wall inside the heating cooker is not particularly defined.

SUMMARY OF THE INVENTION In consideration of the above facts, the present invention provides a heating cooker capable of efficiently heating the side wall inside the heating cooker.

Mode 1: One or more embodiments of the present invention is a heating cooker that is formed in a cylindrical shape with a bottom and has a double-walled structure having a sealed space inside, wherein the inner portion of the heating cooker is A bottomed cylindrical inner container, a bottomed cylindrical outer container that constitutes the outer portion of the heating cooker, and a working fluid injected into the sealed space, wherein The amount of the working fluid is set so as not to cover the entire bottom surface of the closed space , and the portion between the inner bottom wall portion and the inner side wall portion of the inner container is convexly curved to the outside of the inner container. and a radius of the inner corner portion is set to decrease from the inner bottom wall portion toward the inner side wall portion .

Mode 2: According to one or more embodiments of the present invention, the heating cooker is characterized in that the volume ratio of the working fluid to the bottom of the closed space is set to 4 vol% to 80 vol%.

Mode 3: In one or more embodiments of the present invention, the height dimension of the sealed space at the bottom of the heating cooker is at least the width dimension of the sealed space at the side and is 2 mm or more in a vertical cross-sectional view. The heating cooker is characterized by being set to

Mode 4: One or more embodiments of the present invention is a heating cooker characterized in that the sealed space is maintained at a reduced pressure or vacuum of 0.01 atm or less.

Mode 5: In one or more embodiments of the present invention, the inner side wall portion of the inner container or the outer side wall portion of the outer container has a This heating cooker is characterized by being provided with a plurality of pipes used when reducing or evacuating the pressure.

Mode 6: In one or more embodiments of the present invention, a plurality of pipes are arranged at equal intervals in the circumferential direction of the heating cooker, and a cover covering the pipes is attached to the pipes. It is a heating cooker.

Mode 7 : According to one or more embodiments of the present invention, there is provided a heating cooker characterized in that the surfaces of the inner container and the outer container that form the closed space are mirror-finished. .

According to one or more embodiments of the present invention, the sidewalls inside the cooker can be efficiently heated.

FIG. 1 is a vertical cross-sectional view (enlarged cross-sectional view taken along line 1-1 in FIG. 2) of the inner pot according to the first embodiment. FIG. 2 is a top plan view of the inner pot according to the first embodiment. 3 is an enlarged sectional view showing a half of the inner hook shown in FIG. 1; FIG. FIG. 4 is a partially broken plan view from above showing the cover shown in FIG. 1; FIG. 5 is a longitudinal sectional view showing a rice cooker to which the inner pot shown in FIG. 1 is applied. FIG. 6 is a graph showing temperature data of the inner pot and rice when rice is cooked using the inner pot shown in FIG. FIG. 7 is a graph showing temperature data of the inner bottom wall and the outer side wall of the inner pot when rice is cooked using the inner pot shown in FIG. Each case is shown separately. FIG. 7A shows the case where the volume ratio of the working fluid is set to 3 vol%, FIG. 7B shows the case where the volume ratio of the working fluid is set to 10 vol%, and FIG. , shows the case where the volume ratio of the hydraulic fluid is set to 85 vol %. FIG. 8 is an explanatory diagram for explaining how steam rises in the side portion of the sealed space when the inner pot shown in FIG. 1 is heated. FIG. 9 is a longitudinal sectional view corresponding to FIG. 1, showing a modification of the inner hook shown in FIG. FIG. 10(A) is a perspective view showing an example of a variation of connection between the inner bottom wall portion and the outer bottom wall portion shown in FIG. 1, and FIG. FIG. 11 is a perspective view showing another variation of connection with the part; FIG. 11(A) is a vertical cross-sectional view of the inner pot according to the second embodiment (cross-sectional view along line 11A-11A in FIG. 11(B)), and FIG. 11(B) is FIG. is a bottom view of the inner hook shown in FIG. 12A and 12B are explanatory diagrams for explaining a method of manufacturing the inner pot shown in FIG. 11. FIG. FIG. 13 is a longitudinal section of the inner pot according to the third embodiment. FIG. 14(A) is a vertical cross-sectional view of the inner pot (cross-sectional view taken along line 14A-14A in FIG. 14(B)) for explaining variation 1 of the pipe shown in FIG. 14(B) is a bottom view of the inner hook shown in FIG. 14(A); FIG. FIG. 15 is a longitudinal sectional view of the inner pot for explaining variation 2 of the pipe shown in FIG. 11. FIG. Fig. 16(A) is a vertical sectional view showing an example in which a notch is formed in the inner hook shown in Fig. 11, and Fig. 16(B) is an enlarged sectional view of the notch shown in Fig. 16(A). 16(A) is an enlarged sectional view taken along line 16B-16B). FIG. 16(C) is a partial vertical cross-sectional view showing an example in which the notches of FIG. 16(A) are formed in a pipe. 17 is a longitudinal sectional view corresponding to FIG. 1, showing another modification in which the connecting pin is omitted from the inner hook shown in FIG. 1. FIG. 18 is a partial longitudinal sectional view showing a modification of the first flange of the inner container and the second flange of the outer container shown in FIG. 1; FIG.

(First embodiment)
An inner pot 30 as a "cooking device" according to the first embodiment will be described below with reference to FIGS. 1 to 8. FIG. The inner pot 30 constitutes a part of the rice cooker 10 as a pot for cooking rice. Therefore, in the following description, the configuration of the rice cooker 10 will be described first, and then the configuration of the inner pot 30 will be described. An arrow UP appropriately shown in the drawings indicates the upper side of the rice cooker 10 and the inner pot 30 . In the following description, when the up-down direction is indicated, the up-down direction of the rice cooker 10 and the inner pot 30 is indicated unless otherwise specified.

(About rice cooker 10)
As shown in FIG. 5 , the rice cooker 10 is an IH (induction heating) type rice cooker and includes a rice cooker main body 12 and a lid portion 24 .

<Regarding the rice cooker body 12>
The rice cooker main body 12 has an inner pot housing portion 14 for housing an inner pot 30, which will be described later. The inner hook accommodating portion 14 has a concave shape that opens upward, and is formed in a substantially circular shape when viewed from above. A heating section 16 for heating the inner pot 30 is provided below the inner pot accommodating portion 14 . The heating section 16 is composed of an induction coil, and the induction coil is wound in a substantially spiral shape below the inner pot accommodating section 14 .

A power supply unit 18 is provided below the heating unit 16, and the power supply unit 18 applies a high-frequency current to the heating unit 16 (induction coil). As a result, a high-frequency current is applied to the heating unit 16 (induction coil), and an eddy current is generated in the inner pot 30, which will be described later, so that the electric resistance in the inner pot 30 generates heat. It's becoming A temperature sensor 20 is provided below the central portion of the inner pot accommodating portion 14 . This temperature sensor 20 is configured as a sensor that measures the temperature of the bottom of the inner pot 30 . Furthermore, a control section 22 to which the power supply section 18 and the temperature sensor 20 are electrically connected is provided on the top of the rice cooker main body 12 . The control section 22 controls the power supply section 18 based on the output signal from the temperature sensor 20 .

<Regarding the lid portion 24>
The lid portion 24 is rotatably connected to the upper portion of the rice cooker main body 12 by a hinge mechanism 26 to cover the opening of the inner pot accommodating portion 14 . By rotating the lid portion 24 from this state, the opening of the inner hook accommodating portion 14 is opened and closed so that an inner hook 30 described later can be accommodated in the inner hook accommodating portion 14 .

(Regarding the inner pot 30)
As shown in FIGS. 1 to 3, the inner pot 30 is formed in a substantially bottomed cylindrical shape that is open upward, and has a double-walled structure with a sealed space 36 inside. Specifically, the inner pot 30 includes an inner container 32 forming an inner portion of the inner pot 30 and an outer container 34 forming an outer portion of the inner pot 30 . A working fluid 40 is injected into the closed space 36 of the inner pot 30 . Further, the inner pot 30 includes a connecting pin 42 (in a broad sense, an element grasped as a “connecting portion”) that connects the inner container 32 and the outer container 34, and a flange formed at the opening of the inner pot 30. and a cover 50 that covers the Each configuration of the inner hook 30 will be described below.

<Regarding the inner container 32>
The inner container 32 is made of a magnetic material (stainless steel as an example in the present embodiment), and is formed in a substantially bottomed cylindrical shape that opens upward. Specifically, the inner container 32 includes an inner bottom wall portion 32A forming a bottom portion of the inner container 32, a cylindrical inner side wall portion 32B forming a side portion of the inner container 32, an inner bottom wall portion 32A and an inner side wall portion 32B. and an inner corner portion 32C connecting the side wall portions 32B. The inner bottom wall portion 32A is formed in a substantially disc shape with the vertical direction being the plate thickness direction. In addition, the inner bottom wall portion 32A is slightly inclined downward from the central portion toward the outside in the radial direction in a vertical cross-sectional view. In other words, the inner bottom wall portion 32A is slightly curved so that the central portion of the inner bottom wall portion 32A protrudes upward.

The inner corner portion 32C is curved in a substantially quarter elliptical shape so as to protrude outwardly (outwardly and downwardly in the radial direction of the inner container 32) of the inner container 32 in a vertical cross-sectional view, forming the inner bottom wall portion 32A. and the lower end of the inner side wall portion 32B are smoothly connected. Specifically, in a vertical cross-sectional view, the radius R of the inner corner portion 32C is set to decrease from the outer peripheral end portion of the inner bottom wall portion 32A toward the lower end portion of the inner side wall portion 32B. That is, the radius R1 corresponding to the outer peripheral end of the inner bottom wall portion 32A in the radius R is set larger than the radius R2 corresponding to the lower end portion of the inner side wall portion 32B in the radius R.

A first flange 32D projecting radially outward of the inner container 32 is formed at the opening of the inner side wall portion 32B, and the first flange 32D extends over the entire circumferential direction of the inner side wall portion 32B. exist. The first flange 32</b>D is formed by hemming or the like, and is bent into a substantially U-shape that opens radially inward of the inner container 32 . Specifically, the first flange 32D is composed of an upper flange portion 32D1 bent at approximately 90 degrees radially outward of the inner container 32 at the open end of the inner side wall portion 32B, and a tip portion of the upper flange portion 32D1, and a lower flange portion 32</b>D<b>2 that is folded back at approximately 180 degrees on the lower side and radially inward of the inner container 32 . A second flange 34D of the outer container 34, which will be described later, is arranged between the upper flange portion 32D1 and the lower flange portion 32D2, and the second flange 34D is joined to the first flange 32D.

In addition, the inner peripheral surface of the inner container 32 is formed with a layer made of heat-resistant fluororesin, here Teflon (registered trademark). On the other hand, the outer surface of the inner container 32 (specifically, the surface forming the sealed space 36) is mirror-finished.

<Regarding the outer container 34>
Like the inner container 32, the outer container 34 is made of a magnetic material (stainless steel as an example in the present embodiment) and is formed in a substantially cylindrical shape with an open top. Specifically, the outer container 34 includes an outer bottom wall portion 34A forming a bottom portion of the outer container 34, a cylindrical outer side wall portion 34B forming a side portion of the outer container 34, and an outer circumference of the outer bottom wall portion 34A. and an outer corner portion 34C that connects the end portion and the lower end portion of the outer side wall portion 34B. Further, in the present embodiment, the plate thickness of the inner container 32 and the outer container 34 are set to be the same, and the plate thickness of the inner container 32 and the outer container 34 is set to be uniform (constant) as a whole.

The outer side wall portion 34B is formed in a cylindrical shape having a larger diameter than the inner side wall portion 32B of the inner container 32, and is arranged coaxially with the inner container 32 on the radially outer side of the inner side wall portion 32B. Further, the outer bottom wall portion 34A is formed in a circular flat plate shape whose plate thickness direction is the vertical direction, and is arranged below the inner bottom wall portion 32A of the inner container 32 . That is, when the inner pot 30 is accommodated in the inner pot accommodating portion 14 of the rice cooker 10, the outer bottom wall portion 34A is in close contact with the bottom surface of the inner pot accommodating portion 14. As shown in FIG. As with the inner bottom wall portion 32A of the inner container 32, the outer bottom wall portion 34A may be slightly curved so that the central portion of the outer bottom wall portion 34A protrudes upward.

Similarly to the inner corner portion 32C, the outer corner portion 34C is curved in a substantially quarter elliptical shape so as to protrude outward (toward the lower side and radially outward of the outer container 34) of the outer container 34 when viewed in vertical cross section. Thus, the outer peripheral end of the outer bottom wall portion 34A and the lower end of the outer side wall portion 34B are smoothly connected. Specifically, in a vertical cross-sectional view, the radius of the inner corner portion 32C is set to decrease from the outer peripheral end portion of the outer bottom wall portion 34A toward the lower end portion of the outer side wall portion 34B.

A second flange 34D projecting radially outward is formed at the open end of the outer side wall portion 34B. The second flange 34D is bent radially outward of the outer container 34 at approximately 90 degrees at the open end of the outer side wall portion 34B and extends over the entire circumferential direction of the outer side wall portion 34B. A second flange 34D is arranged between the upper flange portion 32D1 and the lower flange portion 32D2 of the first flange 32D of the inner container 32, and is pressed against the first flange 32D to join them. That is, when forming the first flange 32D, the first flange 32D is bent so that the upper flange portion 32D1 and the lower flange portion 32D2 of the first flange 32D press the second flange 34D vertically. As a result, the outer container 34 is assembled to the inner container 32, and between the inner container 32 and the outer container 34, a substantially U-shaped closed space 36 opened upward in a vertical cross-sectional view is formed. there is The tip of the first flange 32D is joined to the second flange 34D by arc welding or the like. In addition to joining the tip portion of the first flange 32D and the second flange 34D, spot welding, seamless welding, laser welding, or the like is applied to the overlapped portion of the first flange 32D and the second flange 34D that overlap in the vertical direction. may be applied to join the two. As a result, the airtightness of the closed space 36 is ensured. Further, the inner surface of the outer container 34 (the surface forming the sealed space 36) is mirror-finished.

Here, the closed space 36 will be described.
As described above, the closed space 36 is formed in a hollow, substantially U-shape when viewed in vertical cross section. In the present embodiment, the bottom portion 36A of the closed space 36 is defined as a region (space) below the inner surface of the inner bottom wall portion 32A of the inner container 32 (a two-dot chain line L1 in FIGS. 1 and 3). (see the area below the position indicated by ). Thus, in the present embodiment, the inner surface of the outer container 34 forming the bottom portion 36A of the sealed space 36 serves as the bottom surface 36B of the sealed space 36, and the bottom surface 36B is the outer bottom wall portion 34A of the outer container 34. and part of the inner surface of the outer corner portion 34C.
Further, the bottom surface 36B stores a hydraulic fluid 40 as will be described later, and when a high frequency current is applied to the heating portion 16 (induction coil), the outer bottom wall portion 34A, which is a magnetic material, generates heat to operate. Liquid 40 is heated.

In the closed space 36, the height dimension H of the bottom portion 36A of the closed space 36 (the vertical dimension between the inner bottom wall portion 32A and the outer bottom wall portion 34A; see FIG. 3) is on the side of the closed space 36. The width dimension W of the portion 36C (the radial dimension of the inner hook 30 between the inner side wall portion 32B and the outer side wall portion 34B, see FIG. 3) or more and is set to 2 mm or more. In this embodiment, the height dimension H of the bottom portion 36A is set to 4 mm, and the width dimension W of the side portion 36C is set to 2 mm. Also, considering the size of the inner pot 30 and the practical level of the inner pot 30 as a pot, it is desirable to set the height dimension H of the bottom portion 36A to 10 mm or less. As described above, the inner bottom wall portion 32A is slightly curved such that the central portion thereof is convex upward, so the height dimension H changes in the radial direction of the inner pot 30. As shown in FIG. Therefore, in this embodiment, the height dimension H is the minimum vertical dimension between the inner bottom wall portion 32A and the outer bottom wall portion 34A. Also, in the drawings, for convenience, the width of the side portion 36C of the sealed space 36 is exaggerated.

Returning to the description of the outer container 34, a circular through hole 34E is formed in the upper portion of the outer side wall portion 34B of the outer container 34 at a position below the second flange 34D. Further, the outer side wall portion 34B of the outer container 34 is provided at a position corresponding to the through hole 34E with a pipe 38 for injecting the working fluid 40 into the sealed space 36 and for evacuating the sealed space 36, which will be described later. there is The pipe 38 is arranged coaxially with the through hole 34E, and the base end of the pipe 38 is joined to the outer side wall portion 34B by arc welding or the like. Thereby, the inside of the closed space 36 and the outside of the inner pot 30 are communicated with each other by the pipe 38 projecting radially outward of the inner pot 30 from the outer side wall portion 34B.

In this embodiment, the hydraulic fluid 40 is injected from the pipe 38 into the closed space 36 . Further, after the hydraulic fluid 40 is injected into the sealed space 36, a vacuum pump (not shown) is attached to the pipe 38, and the air in the sealed space 36 is discharged by the vacuum pump. A reduced pressure of less than 0.1 atm (more preferably a reduced pressure of 0.01 atm or less) or a vacuum is maintained. It should be noted that the pipe for injecting the hydraulic fluid 40 and the pipe for evacuation do not need to be shared, and may be provided separately.

A crimped portion 38A is formed at the tip of the pipe 38, and the tip of the pipe 38 is closed by the crimped portion 38A. Specifically, the tip of the pipe 38 is crimped while the air in the closed space 36 is discharged by a vacuum pump, and the crimped portion is cut to form the crimped portion 38A. Further, the crimped portion 38A is crushed vertically and formed into a substantially plate shape with the vertical direction being the plate thickness direction. Further, the tip of the crimped portion 38A is sealed by arc welding or the like. This ensures the airtightness of the closed space 36 .

<Regarding the hydraulic fluid 40>
In this embodiment, water is used as the hydraulic fluid 40 . Hydraulic fluid 40 is injected into the sealed space 36 from the pipe 38 described above and is stored in the bottom portion 36A of the sealed space 36 . Also, the volume ratio of the hydraulic fluid 40 to the bottom portion 36A of the closed space 36 is set to 4 vol % to 80 vol %. That is, in the state where the hydraulic fluid 40 is stored, the entire bottom portion 36A of the sealed space 36 is not submerged by the hydraulic fluid 40, and the hydraulic fluid 40 and the inner bottom wall portion 32A are above the bottom portion 36A of the sealed space 36. Between, a gap is formed. More specifically, in the present embodiment, the amount of working fluid 40 in closed space 36 is set so that working fluid 40 does not cover the entire bottom surface 36B of bottom portion 36A of closed space 36 . Thus, in a state where the hydraulic fluid 40 is arranged on the bottom surface 36B of the closed space 36, a plurality of droplet-shaped hydraulic fluid 40 are distributed and arranged on the bottom surface 36B. In the present embodiment, as described above, the volume ratio of the hydraulic fluid 40 to the bottom portion 36A of the closed space 36 is set to 4 vol% to 80 vol%. It is desirable to set it to 20 vol%, more preferably 7 vol% to 15 vol%, particularly preferably 8 vol% to 12 vol%.

<Regarding the connecting pin 42>
The connecting pin 42 is made of a magnetic material (stainless steel as an example in the present embodiment). The connecting pin 42 is formed in a substantially cylindrical shape with the vertical direction as the axial direction, and connects the inner bottom wall portion 32A and the outer bottom wall portion 34A of the inner hook 30 . Specifically, the connecting pin 42 includes a center pin 44 that connects the central portion of the inner bottom wall portion 32A and the central portion of the outer bottom wall portion 34A, and a center pin 44 that connects the outer peripheral portion of the inner bottom wall portion 32A and the outer bottom wall portion 34A. and a plurality of (four in the present embodiment) outer peripheral pins 46 that connect with the outer peripheral portion. The outer peripheral pins 46 are arranged at regular intervals (every 90 degrees) in the circumferential direction of the inner hook 30 .

In addition, in the present embodiment, the upper end portion of the connecting pin 42 is joined to the inner bottom wall portion 32A of the inner container 32 by arc welding or the like. On the other hand, the lower end portion of the connecting pin 42 is joined to the outer bottom wall portion 34A of the outer container 34 by laser welding or the like from the outside of the outer container 34 after the inner container 32 and the outer container 34 are assembled. In the present embodiment, the connecting pin 42 includes the center pin 44 and the outer peripheral pin 46. However, the outer peripheral pin 46 may be omitted from the connecting pin 42, and the connecting pin 42 may be the center pin 44 only. good.

<Regarding the cover 50>
As shown in FIGS. 1, 3 and 4, the cover 50 is formed in a circular ring shape and covers the first flange 32D of the inner container 32 and the pipe 38 from the radially outer side of the inner hook 30. there is The cover 50 is made of heat-resistant resin (heat-resistant ABS as an example in the present embodiment). In addition, the cover 50 is divided into two parts by a pair of cover members 52 in plan view. The pair of cover members 52 form a semicircular (substantially C-shaped) opening toward the center of the inner hook 30 in a plan view, and cover the inner hook 30 in a cross-sectional view viewed from the circumferential direction (longitudinal direction). It is formed in a concave shape that is open radially inward. Specifically, the cover member 52 includes an outer peripheral wall 52A forming the outer peripheral portion of the cover member 52, an upper wall 52B extending radially inward of the cover member 52 from the upper end portion of the outer peripheral wall 52A, and an outer peripheral wall 52B. and a lower wall 52C extending radially inward of the cover member 52 from the lower end of 52A. Between the upper wall 52B and the lower wall 52C, a pair of upper and lower intermediate walls 52D extending radially inward from the vertical intermediate portion of the outer peripheral wall 52A are formed. It is arranged parallel to the wall 52B and the lower wall 52C and extends in the circumferential direction of the cover member 52 .

The upper portion (the space between the upper intermediate wall 52D and the upper wall 52B) inside the cover member 52 serves as a first accommodating portion 52E. The cover member 52 is fixed to the inner hook 30 by fitting the first flange 32D of the inner hook 30 into the first accommodating portion 52E. In other words, the cover member 52 covers the first flange 32D (including the second flange 34D) of the inner hook 30 from the radial outside. A lower portion (a space between the lower intermediate wall 52D and the lower wall 52C) inside the cover member 52 serves as a second accommodation portion 52F. The pipe 38 of the inner pot 30 is accommodated in the second accommodation portion 52F. Thereby, the pipe 38 is covered with the cover member 52 from the radially outer side of the inner hook 30 .

Hooks 52G (see FIG. 4) projecting radially outward are formed on the outer peripheral wall 52A of one cover member 52 at both ends in the longitudinal direction. Furthermore, on the outer peripheral wall 52A of the other cover member 52, engaging pieces 52H (see FIG. 4) projecting toward the one cover member 52 are formed at both ends in the longitudinal direction. An engagement hole 52J (see FIG. 4) that engages with the hook 52G is formed in the tip side portion of the. Thereby, the cover 50 covers the first flange 32</b>D and the pipe 38 from the radially outer side of the inner hook 30 while the pair of cover members 52 are engaged.

As for fixing the cover member 52 to the inner hook 30, the hook 52G and the engaging piece 52H may be omitted, and only the first flange 32D may be fitted into the first accommodating portion 52E. Alternatively, the cover member 52 may be fixed to the inner hook 30 by fastening and fixing the cover member 52 to the first flange 32D with screws, rivets, or the like. Further, the cover 50 is not limited to being divided into two pieces, and may be divided into three or more pieces.

(Action and effect)
Next, the operation and effects of this embodiment will be described.
When rice is cooked using the inner pot 30 and the rice cooker 10 configured as described above, the inner pot 30 is accommodated in the inner pot accommodating portion 14 of the rice cooker 10 and heated by the heating portion 16 of the rice cooker 10. Heat the bottom of the kettle 30 . Specifically, a high-frequency current is applied to the heating portion 16 (induction coil) to generate an eddy current in the inner pot 30 . As a result, the bottom of the inner pot 30 generates heat to heat the working fluid 40 in the closed space 36 .

When the temperature of the heated working fluid 40 reaches the boiling point, the working fluid 40 boils and a portion of the working fluid 40 vaporizes. The evaporated steam instantly diffuses into the closed space 36 and heats the inner side wall portion 32B of the inner pot 30 . Then, the steam that has heated the inner side wall portion 32B of the inner pot 30 is condensed and changes from gas to liquid as the working fluid 40 . The liquid working fluid 40 returns to the bottom 36A of the closed space 36 by its own weight. By repeating the phase change cycle in the working fluid 40, the inner side wall portion 32B of the inner pot 30 is heated, and the food (rice) in the inner pot 30 is heated. Since the vapor of the working fluid 40 reaches all wall surfaces of the inner container 32 and the outer container 34 surrounding the sealed space 36 at the same temperature, the inner bottom wall portion 32A, the inner side wall portion 32B, and the inner corner portion 32C of the inner container 32 are at the same temperature. The temperature of the inner container 32 rises while being substantially uniformly heated without delay.

FIG. 6 is a graph showing an example of temperature data of the inner pot 30 and rice when rice is cooked using the inner pot 30 of the present embodiment. In this graph, the horizontal axis indicates time (minutes) from the start of rice cooking, and the vertical axis indicates temperature (°C). Further, the solid line shown in FIG. 6 is the measurement data at the upper portion of the inner side wall portion 32B of the inner pot 30, and the dotted line is the measurement data at the center portion of the inner bottom wall portion 32A of the inner pot 30. is the measurement data of the upper part of the rice in the inner pot 30, and the two-dot chain line is the measurement data of the lower part of the rice in the inner pot 30.

Then, as shown in this figure, at the start of the "rice cooking section" which starts approximately 20 minutes after the start of rice cooking, the temperature of the inner side wall portion 32B of the inner pot 30 is higher than that of the inner bottom wall portion 32A of the inner pot 30. It can be seen that the temperature rises to 100° C. in the same manner as the temperature. In addition, even in the “rice cooking section” and the “steaming section” after the temperature of the inner pot 30 reaches 100° C., there is almost no temperature difference between the inner side wall portion 32B and the inner bottom wall portion 32A. It can be seen that the inner pot 30 is being heated.

Furthermore, at the start of the "rice cooking section", it can be seen that the temperature of the upper and lower portions of the rice rises following the temperature rise of the inner side wall portion 32B and the inner bottom wall portion 32A of the inner pot 30. In other words, the rice can be cooked by reducing the temperature difference between the inner side wall portion 32B and the inner bottom wall portion 32A of the inner pot 30 and the upper and lower portions of the rice.

In addition, in the present embodiment, it was found that rice can be cooked in a short time even in so-called quick rice cooking in which the "soaking section" in rice cooking is omitted and rice is cooked in the "rice cooking section" immediately after the start of rice cooking. That is, in general, when performing quick-cooking rice cooking, the heating unit of the rice cooker 10 is placed in the middle of cooking rice in order to prevent excessive evaporation of the water in which the rice is soaked during quick-cooking rice cooking (hereinafter referred to as "flooding"). 16 (induction coil) is controlled to be lower than the output at the start of rice cooking. For this reason, the output is temporarily lowered during rice cooking, and the time until the completion of rice cooking in quick cooking rice cooking is lengthened.

On the other hand, in the case of quick rice cooking using the inner pot 30 of the present embodiment, it was found that excessive evaporation of the soaked water during quick cooking rice can be suppressed. For this reason, even if the output to the heating unit 16 (induction coil) of the rice cooker 10 is set to a constant output from the start to the end of rice cooking to heat the inner pot 30, the rice cooked by normal rice cooking does not cook. It was confirmed that it is possible to cook rice that is not Thus, by setting the output to the heating unit 16 (induction coil) of the rice cooker 10 to a constant output from the start of rice cooking to the end, it is possible to further shorten the time for quick rice cooking.

Here, in the inner pot 30 of the present embodiment, the volume ratio of the hydraulic fluid 40 to the bottom portion 36A of the closed space 36 is set to 4 vol % to 80 vol %. Specifically, a plurality of hydraulic fluids 40 are injected onto the bottom surface 36B of the sealed space 36 in the form of droplets so as not to cover the entire bottom surface 36B of the sealed space 36 . Thereby, the inner side wall portion 32B of the inner container 32 can be efficiently heated.

This point will be described below using the graph shown in FIG. The graph shown in FIG. 7 shows an example of data obtained by measuring the temperature of the inner pot 30 when the volume ratio of the working fluid 40 to the bottom portion 36A is changed while the inner pot 30 is cooking rice. In each graph of FIG. 7, the horizontal axis indicates time (minutes) from the start of rice cooking, and the vertical axis indicates temperature (° C.). In addition, the solid line in each graph is the measurement data at the upper portion of the inner side wall portion 32B of the inner pot 30, the dotted line is the measurement data at the lower portion of the inner side wall portion 32B, and the dashed line is the inner bottom of the inner pot 30. It is the measurement data of the central portion of the wall portion 32A, and the two-dot chain line is the measurement data of the outer peripheral portion of the inner bottom wall portion 32A. Furthermore, in FIG. 7A, the volume ratio is set to 3 vol%, in FIG. 7B, the volume ratio is set to 10 vol%, and in FIG. 7C, the volume ratio is set to 80 vol%. It is set to a large value (approximately 85 vol%).

As shown in FIG. 7(A), when the volume ratio is set to 3 vol % or less, the cycle of phase change in the working fluid 40 (the cycle of vaporizing from liquid to vapor, condensing from vapor and returning to liquid) It has been found that the temperature rise behavior of the entire inner pot 30 is unstable, although the cycle) is occurring.

Further, as shown in FIG. 7(C), when the volume ratio exceeds 80 vol %, the cycle efficiency of the phase change of steam decreases, and the inner bottom wall portion 32A and the inner side wall portion 32B of the inner pot 30 It was found that the temperature difference between the inner pot 30 and the temperature uniformity in the entire inner pot 30 could not be obtained.

On the other hand, as shown in FIG. 7B, when the volume ratio is set to 10 vol %, the phase change cycle of the steam is performed well, and the inner bottom wall portion 32A and the inner side wall portion 32B of the inner pot 30 It was found that the temperature of the entire inner pot 30 rises while the temperature difference between them is suppressed, and that the entire inner pot 30 is heated substantially uniformly.
As described above, by setting the volume ratio of the hydraulic fluid 40 to the bottom portion 36A in the closed space 36 to 4 vol% to 80 vol%, the inner side wall portion 32B of the inner container 32 is efficiently heated, and the entire inner pot 30 is substantially uniformly heated. can be heated to

Further, in the inner pot 30, the height dimension H of the bottom portion 36A of the sealed space 36 is set to be greater than or equal to the width dimension W of the side portions 36C and 2 mm or more. Therefore, the inner side wall portion 32B of the inner container 32 can be heated more efficiently.
That is, if the height dimension H is set to be smaller than the width dimension W and less than 2 mm, the working fluid 40 that condenses and returns to liquid in the cycle of the phase change in the working fluid 40 will flow from the side portion 36C of the closed space 36. It has been found that the return efficiency to the bottom portion 36A is reduced and the uniform heating effect for the inner pot 30 is reduced. Therefore, as described above, by setting the height dimension H to be greater than or equal to the width dimension W and 2 mm or more, the working fluid 40 that has condensed and returned to the liquid state will flow from the side portion 36C of the sealed space 36 to the bottom portion 36A. It is possible to suppress a decrease in return efficiency to the inner pot 30 and enhance the effect of uniformly heating the inner pot 30 . As described above, the inner side wall portion 32B of the inner container 32 can be heated more efficiently.

Furthermore, the inside of the closed space 36 is set to be maintained at a reduced pressure of less than 0.1 atm (more preferably, a reduced pressure of 0.01 atm or less) or a vacuum. Therefore, the inner side wall portion 32B of the inner container 32 can be heated more efficiently.

That is, as shown in FIG. 8, the steam generated in the closed space 36 rises along the inner side wall portion 32B of the inner pot 30 (see arrows in FIG. 8). At this time, if the pressure in the sealed space 36 exceeds 0.1 atm, the residual air A (see the part indicated by the two-dot chain line) in the sealed space 36 rises along the inner side wall portion 32B. The vapor pushes up to the upper end side of the closed space 36 . That is, in this case, the remaining air A in the closed space 36 acts as a resistance layer against the rising steam, and tends to hinder the rising of the steam. By reducing the pressure in the sealed space 36 to less than 0.1 atm, the resistance of the residual air A against the rising steam is reduced, causing the steam to rise to the upper end side of the sealed space 36, and the inner side wall portion 32B. It can be heated well by steam. Further, by maintaining the inside of the sealed space 36 at a reduced pressure of 0.01 atm or less or in a vacuum, the inner side wall portion 32B can be more effectively heated by steam. Therefore, by setting the inside of the closed space 36 to be kept at a reduced pressure of less than 0.1 atm (more preferably, a reduced pressure of 0.01 atm or less) or a vacuum, the inner side wall portion 32B of the inner container 32 can be moved more efficiently. Can be heated.

Also, the radius R of the inner corner portion 32C of the inner hook 30 is set to decrease from the outer peripheral end portion of the inner bottom wall portion 32A toward the lower end portion of the inner side wall portion 32B. That is, the radius R1 corresponding to the outer peripheral end of the inner bottom wall portion 32A in the radius R is set larger than the radius R2 corresponding to the lower end portion of the inner side wall portion 32B in the radius R. As a result, while suppressing a decrease in the capacity of the inner pot 30 (the amount of rice that can be cooked), the steam generated in the sealed space 36 is effectively directed toward the inner side wall portion 32B along the inner corner portion 32C of the inner pot 30. can be raised. This point will be described below.

That is, if the radius R of the inner corner portion 32C is set constant as the radius R1 corresponding to the outer peripheral end portion of the inner bottom wall portion 32A without changing the radial size of the inner hook 30 (hereinafter referred to as , this case will be referred to as a comparative example), the lower portion of the inner corner portion 32C enters more inward in the radial direction than in the present embodiment. That is, the diameter dimension of the inner bottom wall portion 32A is reduced. As a result, the capacity of the inner pot 30 tends to decrease in the comparative example.
In the comparative example, the angle of inclination of the tangential line contacting the inner corner portion 32</b>C with respect to the horizontal direction gradually increases toward the outer side in the radial direction of the inner container 32 in a vertical cross-sectional view.

In contrast, in the present embodiment, the radius R of the inner corner portion 32C of the inner container 32 is set to decrease from the outer peripheral portion of the inner bottom wall portion 32A toward the lower end portion of the inner side wall portion 32B. there is Therefore, in a vertical cross-sectional view, the angle of inclination of the tangent line contacting the inner corner portion 32C with respect to the horizontal direction sharply increases radially outward of the inner container 32 compared to the comparative example. In other words, the inner corner portion 32C is formed to rise sharply compared to the comparative example. As a result, resistance to the steam rising along the inner corner portion 32C of the inner pot 30 is reduced compared to the comparative example, and the steam can be effectively raised toward the inner side wall portion 32B.
Further, in the present embodiment, the lower end portion of the inner corner portion 32C can be arranged radially outward compared to the comparative example. That is, the diameter of the inner bottom wall portion 32A can be increased compared to the comparative example. Thereby, the capacity of the inner pot 30 can be increased as compared with the comparative example.
As described above, according to the inner pot 30 of the present embodiment, the steam in the sealed space 36 is directed along the inner corner portion 32C of the inner container 32 to the inner side wall portion 32B while suppressing a decrease in the capacity of the inner pot 30. can be effectively lifted to the side.

Further, the surface of the inner pot 30 forming the sealed space 36 is mirror-finished. Therefore, when the steam rises along the inner corner portion 32C and the inner side wall portion 32B of the inner pot 30 in the closed space 36, the resistance of these wall surfaces to the steam can be reduced. As a result, the steam in the closed space 36 can be favorably raised to the upper end side of the closed space 36 . As a result, the entire inner container 32 can be efficiently heated.
In addition, the resistance of these wall surfaces to the working fluid 40 can be reduced when the working fluid 40 that has condensed into a liquid descends. As a result, the working fluid 40 can be returned to the bottom portion 36A of the closed space 36 satisfactorily.

A connecting pin 42 is provided in the closed space 36 of the inner pot 30 , and the connecting pin 42 connects the inner bottom wall portion 32A and the outer bottom wall portion 34A of the inner pot 30 . When the inner pot 30 is heated, the air pressure in the closed space 36 rises, and the inner bottom wall portion 32A and the outer bottom wall portion 34A tend to expand vertically. At this time, since the inner bottom wall portion 32A and the outer bottom wall portion 34A are connected by the connecting pin 42, the inner bottom wall portion 32A and the outer bottom wall portion 34A act to pull each other. As a result, the upward expansion of the inner bottom wall portion 32A and the downward expansion of the outer bottom wall portion 34A during heating of the inner pot 30 can be suppressed by the connecting pin 42, and the inner pot 30 is heated. Deformation at the bottom can be suppressed.

Furthermore, the connecting pin 42 is configured by a pin whose axial direction is the vertical direction. Therefore, the inner bottom wall portion 32A and the outer bottom wall portion 34A can be connected by the connecting pin 42 without impeding the flow of the working fluid 40 and the vapor that has become gas in the bottom portion 36A of the closed space 36. .

Further, the connecting pin 42 has a center pin 44, and the center pin 44 connects the central portion of the inner bottom wall portion 32A and the central portion of the outer bottom wall portion 34A of the inner hook 30. As shown in FIG. Therefore, the vertical displacement of the center portions of the inner bottom wall portion 32A and the outer bottom wall portion 34A can be suppressed by the connecting pin 42 . Thereby, it is possible to suppress the displacement of the portion of the inner bottom wall portion 32A and the outer bottom wall portion 34A that undergoes the largest amount of displacement during inflation. Therefore, expansion of the inner bottom wall portion 32A and the outer bottom wall portion 34A can be effectively suppressed.

Further, a pipe 38 projecting radially outward of the inner pot 30 is provided on the outer side wall portion 34B of the inner pot 30 . Before the crimped portion 38A of the pipe 38 is formed, the inside of the sealed space 36 of the inner pot 30 and the outside of the inner pot 30 are communicated by the pipe 38 . Accordingly, the hydraulic fluid 40 can be easily injected into the sealed space 36 using the pipe 38 . By attaching a vacuum pump to the pipe 38, the air in the closed space 36 can be discharged from the pipe 38, and the inside of the closed space 36 can be decompressed or vacuumed. Therefore, it is possible to improve workability when manufacturing the inner pot 30 .

Further, in the inner hook 30 , the first flange 32</b>D (second flange 34</b>D) of the inner hook 30 and the pipe 38 are covered from the radially outer side of the inner hook 30 with a cover 50 . Therefore, even if the pipe 38 for improving the workability in manufacturing the inner hook 30 is provided on the outer side wall portion 34B, the pipe 38 can be made invisible by the cover 50 . Also, the cover 50 can be used as a handle for the inner hook 30 . As described above, it is possible to improve the design of the inner pot 30 and improve the convenience for the user.

Further, in the inner hook 30, the first flange 32D of the inner container 32 is pressed against the second flange 34D of the outer container 34 by hemming or the like so as to wrap around the second flange 34D of the outer container 34. As shown in FIG. That is, the mating portion of the inner container 32 and the outer container 34 forms a so-called labyrinth structure (maze structure) and is closed. As a result, airtightness in the closed space 36 formed by the inner container 32 and the outer container 34 can be ensured.

Further, in the present embodiment, as described above, the inner pot 30 has a double-walled structure with the closed space 36 inside, and the inside of the closed space 36 is in a decompressed or vacuum state. Therefore, it is possible to improve the heat retention of the inner pot 30 after the rice is cooked.

(Modified example of inner pot 30)
Next, an inner hook 60 of a modified example will be described with reference to FIG.
The inner pot 60 of the modified example is configured similarly to the inner pot 30 of the first embodiment except for the following points. In addition, in FIG. 9, the same reference numerals are given to the parts configured in the same manner as in the first embodiment.

That is, in the inner pot 60 of the modified example, a portion of the bottom portion of the inner pot 60 is formed in a solid shape. Specifically, the inner bottom wall portion 32A is omitted from the inner container 32, and the inner container 32 is formed in a substantially cylindrical shape. Further, the outer bottom wall portion 34A is omitted from the outer container 34, and the outer container 34 is formed in a substantially cylindrical shape. A substantially solid disc-shaped bottom plate 62 is provided radially inward of the inner hook 60 with respect to the inner corner portion 32C of the inner container 32 and the outer corner portion 34C of the outer container 34 . The bottom plate 62, like the inner container 32 and the outer container 34, is made of a magnetic material (stainless steel as an example in this example). The outer peripheral portion of the bottom plate 62 is joined to the inner corner portion 32C and the outer corner portion 34C by arc welding or the like.

Thus, in the inner pot 60, the closed space 36 is a space between the inner corner portion 32C and the inner side wall portion 32B and the outer corner portion 34C and the outer side wall portion 34B. A portion of the inside of the corner portion of the inner pot 60 (the portion between the inner corner portion 32C and the outer corner portion 34C) constitutes the bottom portion 36A of the sealed space 36. As shown in FIG. In the inner pot 60, since the bottom portion of the inner pot 60 is composed of the bottom plate 62, the connecting pin 42 in the inner pot 30 of the present embodiment is omitted.

Also in the inner pot 60 of the modified example, when the bottom portion (bottom plate 62) of the inner pot 60 is heated, the hydraulic fluid 40 injected into the closed space 36 is heated. When the temperature of the heated working fluid 40 reaches the boiling point, the working fluid 40 boils and a portion of the working fluid 40 vaporizes. Then, the evaporated steam rises along the inner corner portion 32C and the inner side wall portion 32B in the closed space 36 toward the side portion 36C inside the closed space 36 . Thereby, the inner side wall portion 32B of the inner pot 60 is heated by the steam. Also, the steam that has heated the inner side wall portion 32B is condensed and changes from gas to liquid as the working fluid 40 . Further, the hydraulic fluid 40 that has changed to liquid descends due to its own weight and returns to the bottom portion 36A of the sealed space 36. As shown in FIG. By repeating the phase change cycle in the working fluid 40, the inner side wall portion 32B of the inner container 32 is heated. As described above, in the inner pot 60 of the modified example, the inner side wall portion 32B of the inner pot 60 can be efficiently heated as in the first embodiment.

Further, in the inner pot 60 of the modified example, the bottom portion 36A of the closed space 36 is set within the corner portion of the inner pot 60 . Therefore, when the working fluid 40 is vaporized into vapor, the vapor can be immediately moved (raised) toward the side portion 36C of the sealed space 36 along the inner corner portion 32C. Therefore, the vaporized steam can be efficiently moved (raised) to the side portion 36C of the closed space 36 to heat the inner side wall portion 32B of the inner pot 60 .

In addition, in the inner pot 60 of the modified example, the closed space 36 of the inner pot 60 is a space between the inner corner portion 32C and the inner side wall portion 32B and the outer corner portion 34C and the outer side wall portion 34B. The closed space 36 may be the space between the outer corner portion 34C and the outer side wall portion 34B. In other words, the closed space 36 should include at least the space between the outer corner portion 34C and the outer side wall portion 34B. In this case, the portion of the inner hook 60 below the chain double-dashed line L2 in FIG. 9 is formed in a solid shape.

(Regarding variations in the method of connecting the inner bottom wall portion 32A and the outer bottom wall portion 34A of the inner pot 30)
Next, two variations of the method of connecting the inner bottom wall portion 32A and the outer bottom wall portion 34A of the inner pot 30 will be described.

(Variation 1 of connection method)
Variation 1 of the connection method will be described below with reference to FIG. 10(A). Variation 1 is configured in the same manner as the first embodiment except for the following points. In addition, in FIG. 10(A), the same code|symbol is attached|subjected to the components comprised similarly to 1st Embodiment.

That is, in variation 1, the connecting pin 42 is omitted, and a connecting plate 70 (broadly understood as a "connecting portion") is provided between the inner bottom wall portion 32A and the outer bottom wall portion 34A of the inner hook 30. elements) are provided. The connection plate 70 is formed in a substantially cross shape in plan view. Specifically, the connection plate 70 includes a first connection plate 72 and a pair of second connection plates 74 . The first connecting plate 72 and the second connecting plate 74 are formed in a substantially elongated plate shape, and the longitudinal length of the first connecting plate 72 is larger than the longitudinal length of the second connecting plate 74 . is set to approximately double. One end in the longitudinal direction of the second connecting plate 74 is joined to the central portion in the longitudinal direction of the first connecting plate 72 , and the second connecting plate 74 extends from the central portion in the longitudinal direction to the plate thickness of the first connecting plate 72 . extending in both directions. As a result, four connecting pieces 70A are formed on the connecting plate 70, and the connecting pieces 70A radially extend from the central portion of the connecting plate 70. As shown in FIG.

Then, the connecting plate 70 is connected to the inner bottom wall portion 32A and the outer bottom wall portion so that the central portion of the connecting plate 70 overlaps the central portions of the inner bottom wall portion 32A and the outer bottom wall portion 34A of the inner pot 30 in plan view. It is arranged between the portions 34A. Further, the upper end portion of the connecting plate 70 is joined to the inner bottom wall portion 32A, and the lower end portion of the connecting plate 70 is joined to the outer bottom wall portion 34A. Thereby, the inner bottom wall portion 32A and the outer bottom wall portion 34A are connected by the connecting plate 70 . Also, in this state, the bottom portion 36A of the sealed space 36 is partitioned by the connecting plate 70. As shown in FIG.

Further, a plurality of communication holes 70B are formed at the lower end of each connecting piece 70A of the connecting plate 70. As shown in FIG. As a result, the bottom portion 36A of the sealed space 36 partitioned by the connecting plate 70 is communicated with the communicating hole 70B so that the hydraulic fluid 40 in the bottom portion 36A can flow in the bottom portion 36A of the partitioned sealed space 36. It is configured.

In Variation 1, the inner bottom wall portion 32A and the outer bottom wall portion 34A are connected by the connecting plate 70 as described above. Therefore, similarly to the present embodiment, expansion of the inner bottom wall portion 32A and the outer bottom wall portion 34A when the inner pot 30 is heated can be suppressed.

Further, in Variation 1, the connecting piece 70A of the connecting plate 70 radially extends from the central portion of the inner bottom wall portion 32A and the outer bottom wall portion 34A to connect the inner bottom wall portion 32A and the outer bottom wall portion 34A. doing. Therefore, when the inner pot 30 is heated, the heat transferred to the connecting plate 70 can be transferred radially across the inner bottom wall portion 32A by the connecting piece 70A. Thereby, the inner bottom wall portion 32A can be substantially uniformly heated by the connecting piece 70A in the radial direction of the inner bottom wall portion 32A.

Further, a plurality of communication holes 70B are formed at the lower end of each connecting piece 70A of the connecting plate 70. As shown in FIG. Therefore, even if the connecting plate 70 is arranged to partition the bottom portion 36A of the closed space 36, the hydraulic fluid 40 in the bottom portion 36A does not flow inside the bottom portion 36A of the closed space 36 partitioned by the connecting plate 70. can be done.

In variation 1, four connection pieces 70A are formed on the connection plate 70, but the number of connection pieces 70A can be set arbitrarily.

(Variation 2 of connection method)
Variation 2 of the connection method will be described below with reference to FIG. 10(B). Variation 2 is configured in the same manner as the first embodiment except for the following points. In addition, in FIG. 10(B), the same code|symbol is attached|subjected to the component comprised similarly to 1st Embodiment.

That is, in variation 2, a substantially disk-shaped intermediate plate 80 is provided between the connecting pin 42 and the inner bottom wall portion 32A of the inner hook 30, and the intermediate plate 80 is similar to the connecting pin 42 in that it is magnetic. It is composed of a body (stainless steel as an example in this modified example). That is, in variation 2, the intermediate plate 80 is interposed between the connecting pin 42 and the inner bottom wall portion 32A of the inner hook 30, and the intermediate plate 80 is joined to the connecting pin 42 and the inner bottom wall portion 32A. Therefore, when the inner pot 30 is heated, the heat transferred by the connecting pin 42 is dispersed by the intermediate plate 80 and transferred to the entire inner bottom wall portion 32A of the inner pot 30 . Thus, in Variation 2, the inner bottom wall portion 32A of the inner pot 30 can be uniformly heated in the radial direction while suppressing expansion of the inner bottom wall portion 32A and the outer bottom wall portion 34A during heating.

(Second embodiment)
An inner pot 90 as a "cooking device" according to the second embodiment will be described below with reference to FIGS. 11 and 12. FIG.
The inner pot 90 of the second embodiment is constructed in the same manner as the inner pot 30 of the first embodiment except for the following points. In addition, in FIG. 11, the same reference numerals are given to the parts configured in the same manner as in the first embodiment. Also, in FIG. 11, the cover 50 of the inner hook 90 is omitted.

As shown in FIGS. 11A and 11B, in the inner pot 90, the inner bottom wall portion 32A of the inner container 32 is substantially horizontal along a plane perpendicular to the vertical direction (outside of the outer container 34). (substantially parallel to the bottom wall portion 34A). Further, in the inner pot 90, the connecting pin 42 of the first embodiment is omitted, and the outer bottom wall portion 34A of the outer container 34 is provided with a plurality of (three in this embodiment) connecting recesses 34F (broadly defined). , which is an element grasped as a “connecting portion”) is formed. The connecting concave portion 34F is formed in a substantially inverted U-shaped concave shape that opens downward when viewed in longitudinal section, and protrudes upward from the outer bottom wall portion 34A. The three connecting recesses 34F are arranged radially outward of the inner pot 90 with respect to the central portion of the outer bottom wall portion 34A, and are arranged at equal intervals (every 120 degrees) in the circumferential direction of the inner pot 90. It is The top of the connecting concave portion 34F is arranged adjacent to the lower surface of the inner bottom wall portion 32A of the inner container 32 and is joined to the inner bottom wall portion 32A by spot welding. Thereby, the inner bottom wall portion 32A and the outer bottom wall portion 34A are connected by the connecting concave portion 34F. As described above, in the second embodiment, the inner bottom wall portion 32A of the inner container 32 is arranged substantially horizontally along a plane perpendicular to the vertical direction. 32A may be slightly curved so as to protrude upward.

Further, in the first flange 32D of the inner container 32, the lower flange portion 32D2 of the first embodiment is omitted. Then, the first flange 32D (upper flange portion 32D1) of the inner container 32 and the second flange 34D of the outer container 34 are arranged so as to overlap vertically, and the tip of the first flange 32D and the second flange 34D of the outer container 34 The tip of the flange 34D is joined by laser welding or the like. In addition to joining the tip portion of the first flange 32D and the tip portion of the second flange 34D, spot welding, seamless welding, laser welding, or the like may be applied to overlapping portions of the first flange 32D and the second flange 34D that overlap vertically. is applied to join the two.

Furthermore, in the inner pot 90, a sealing material 92 containing glass frit is provided inside the tip of the pipe 38, and the opening of the pipe 38 is sealed by the sealing material 92, so that the inside of the closed space 36 is closed. Confidentiality is ensured.

Next, a method for manufacturing the inner pot 90 according to the second embodiment will be described with reference to FIG. 12 .
As shown in FIG. 12(a), in the method of manufacturing the inner pot 90, first, the inner container 32 and the outer container 34 are formed by pressing (deep drawing) (pressing step). In this pressing step, the connecting concave portion 34F is also formed in the outer bottom wall portion 34A of the outer container 34. As shown in FIG.
After the pressing step, as shown in FIG. 12B, the upper portion of the outer side wall portion 34B of the outer container 34 is drilled to form a through hole 34E in the outer container 34 (piercing step).

After the perforating step, the inner container 32 is placed inside the outer container 34 as shown in FIG. 12(c). Specifically, the inner bottom wall portion 32A of the inner container 32 is placed on the top of the connecting recess 34F of the outer container 34, and the first flange 32D of the inner container 32 is placed above the second flange 34D of the outer container 34. Place them so that they overlap. Then, the tip of the first flange 32D of the inner container 32 and the tip of the second flange 34D of the outer container 34 are laser-welded to join the two tips (flange joining step). As a result, the inner container 32 and the outer container 34 are connected to form a closed space 36 inside the inner pot 90 .
In addition, in the flange joining step, in addition to joining the front end portion of the first flange 32D and the front end portion of the second flange 34D, spot welding and seamless welding are performed on overlapping portions of the first flange 32D and the second flange 34D that overlap vertically. , laser welding or the like is applied to join them (FIG. 12(c) shows an example of spot welding). In the case of laser welding, laser welding is performed from the upper side of the first flange 32D or the lower side of the second flange 34D to join the two. In this case, considering the design of the inner hook 90, it is desirable to perform laser welding from the lower side of the second flange 34D.

As shown in (d) of FIG. 12, after the flange joining process, a pair of upper and lower guns for spot welding are arranged above the inner bottom wall portion 32A of the inner container 32 and in the connecting concave portion 34F of the outer container 34. Then, the inner bottom wall portion 32A and the top portion of the connecting concave portion 34F are joined by spot welding (bottom joining step). Thereby, the inner bottom wall portion 32A of the inner container 32 and the outer bottom wall portion 34A of the outer container 34 are connected.

As shown in (e) of FIG. 12, after the pot bottom joining step, the base end of the pipe 38 is inserted into the through hole 34E of the outer container 34, and the base end of the pipe 38 is attached to the edge of the through hole 34E. The parts are joined by arc welding (vacuum mouthpiece joining process). As a result, a pipe 38 is provided in the outer container 34 , and the inside of the closed space 36 and the outside of the inner pot 90 are communicated with each other through the pipe 38 .

As shown in FIG. 12(f), after the vacuum mouthpiece bonding process, the inner peripheral surface of the inner container 32 is subjected to a fluorine coating treatment to form a layer made of a fluorine resin (Teflon), A coating treatment is applied to the outer peripheral surface of the outer container 34 to form a layer composed of a heat-resistant paint (surface treatment step).

As shown in (g) of FIG. 12 , after the surface treatment process, the working fluid 40 is injected into the sealed space 36 from the pipe 38 . After the hydraulic fluid 40 is injected into the closed space 36 , the air inside the closed space 36 is discharged using a vacuum sealing device, and the pipe 38 is sealed using the sealing material 92 . Specifically, the air in the sealed space 36 is discharged by the vacuum pump of the vacuum sealing device, and when the air pressure in the sealed space 36 falls below a predetermined value, the sealing material 92 is inserted into the pipe 38 by the vacuum sealing device. to fill. The vacuum sealing device also has a spiral induction coil into which the pipe 38 is inserted. Then, by applying a high-frequency current to the induction coil, the pipe 38 is locally induction-heated and the sealing material 92 is melted. After that, the pipe 38 is cooled and sealed with the sealing material 92 (vacuum sealing process).

As shown in (h) of FIG. 12, after the vacuum sealing process, the pipe 38 is cut at its longitudinal intermediate portion (cutting process).
After the cutting step, as shown in (i) of FIG. 12, the pair of cover members 52 (cover 50) are assembled to the first flange 32D of the inner container 32 and the second flange 34D of the outer container 34 (cover assembly). process).
Thus, the manufacture of the inner pot 90 is completed.
The manufacturing process of the inner pot 90 may be performed in a vacuum environment (within a vacuum chamber) evacuated by a vacuum device. In this case, all the steps shown in (a) to (i) of FIG. 12 may be performed in a vacuum environment, or the pressing step shown in (a) of FIG. The drilling step shown in b) and the subsequent steps may be performed in a vacuum environment. As a result, in the vacuum sealing step shown in (g) of FIG. 12, since the inner pot 90 is already in a vacuum environment, the vacuuming step can be omitted. In this case, the outer container 34 may be vacuum-sealed by omitting the pipe for vacuuming and welding a metal plate material covering (closing) the through hole 34E from the outside to the outer container 34 . Glass frit may be used as the vacuum sealing material. Further, in this case, since the hydraulic fluid 40 can be injected into the sealed space 36 from the through hole 34E in a solid (ice) state, a pipe for injecting the hydraulic fluid can be omitted.
As a result, the inner pot 90 can be manufactured without protrusions such as pipes on either the inner container 32 or the outer container 34 . Therefore, since the inner pot 90 does not have a pipe, the inner pot 90 can be easily washed, the usability of the inner pot 90 can be improved, and the design of the inner pot 90 can be improved. can do.

Also in the second embodiment, when the bottom portion of the inner pot 90 is heated, the working fluid 40 injected into the closed space 36 is heated. When the temperature of the heated working fluid 40 reaches the boiling point, the working fluid 40 boils and a portion of the working fluid 40 vaporizes. Then, the evaporated steam rises along the inner corner portion 32C and the inner side wall portion 32B in the closed space 36 toward the side portion 36C inside the closed space 36 . Thereby, the inner side wall portion 32B of the inner pot 90 is heated by the steam. Also, the steam that has heated the inner side wall portion 32B is condensed and changes from gas to liquid as the working fluid 40 . Further, the hydraulic fluid 40 that has changed to liquid descends due to its own weight and returns to the bottom portion 36A of the sealed space 36. As shown in FIG. By repeating the phase change cycle in the working fluid 40, the inner side wall portion 32B of the inner container 32 is heated. As described above, in the inner pot 90 of the second embodiment, similarly to the first embodiment, the inner side wall portion 32B of the inner pot 90 is efficiently heated, and the entire inner pot 90 is heated substantially uniformly. can do.

Further, in the inner pot 90 of the second embodiment, a plurality of connecting recesses 34F are formed in the outer bottom wall portion 34A of the outer container 34, and the connecting recesses 34F are spotted on the inner bottom wall portion 32A of the inner container 32. They are joined by welding or the like. Thereby, the inner bottom wall portion 32A and the outer bottom wall portion 34A can be connected with a simple configuration. In addition, compared to the first embodiment, the number of parts can be reduced, and the manufacturing man-hours can be reduced.

Further, in the inner pot 90 of the second embodiment, the tip of the first flange 32D of the inner container 32 and the tip of the second flange 34D of the outer container 34 are joined by laser welding or the like. Further, overlapping portions of the first flange 32D and the second flange 34D are joined by spot welding, seamless welding, laser welding, or the like. Thereby, the joint strength between the first flange 32D and the second flange 34D can be increased, and the rigidity of the opening of the inner hook 90 can be increased. As a result, deformation of the inner container 32 can be suppressed when the inner pot 90 is heated.

That is, for example, in joining (welding) only the tip of the first flange 32D and the tip of the second flange 34D, when the inner pot 90 is heated, the internal pressure of the closed space 36 rises, causing the inner container 32 to move to the second position. There is a possibility that the tip of the 1 flange 32D will be lifted up. On the other hand, by joining the overlapping portions of the first flange 32D and the second flange 34D, the rigidity of the opening of the inner hook 90 is increased. As a result, deformation of the inner container 32 can be suppressed when the inner pot 90 is heated, and a good joint state between the first flange 32D and the second flange 34D can be maintained.

In the second embodiment, a plurality of connecting recesses 34F are formed in the outer bottom wall portion 34A of the outer container 34, but one connecting recess 34F may be formed in the outer bottom wall portion 34A. . In this case, the connecting recess 34F may be arranged in the central portion of the outer bottom wall portion 34A, and the top portion of the connecting recess 34F and the central portion of the inner bottom wall portion 32A may be joined.

(Third Embodiment)
An inner pot 100 as a "cooking device" according to the third embodiment will be described below with reference to FIG.
The inner pot 100 of the third embodiment is constructed in the same manner as the inner pot 30 of the first embodiment except for the following points. In addition, in FIG. 13, the same reference numerals are given to the parts configured in the same manner as in the first embodiment. Also, in FIG. 13, the cover 50 of the inner hook 100 is omitted.

In the third embodiment, the connecting pin 42 of the first embodiment is omitted from the inner hook 100 . An inner bottom wall portion 32A of the inner container 32 is formed with a constricted portion 32G that protrudes upward. The constricted portion 32G is formed in a substantially disc shape concentric with the inner bottom wall portion 32A, and the outer peripheral portion of the constricted portion 32G is smoothly curved and connected to the inner bottom wall portion 32A. As an example, the diameter of the narrowed portion 32G is set to 60% of the diameter of the inner bottom wall portion 32A, and the height of the narrowed portion 32G is set to 3 mm.

Further, the outer bottom wall portion 34A of the outer container 34 is formed with a narrowed portion 34G configured similarly to the narrowed portion 32G. That is, the constricted portion 34G is formed in a substantially disc shape concentric with the outer bottom wall portion 34A and protrudes upward from the outer bottom wall portion 34A. Further, the outer peripheral portion of the narrowed portion 34G is smoothly curved and connected to the outer bottom wall portion 34A. Furthermore, as an example, the diameter of the narrowed portion 34G is set to 60% of the diameter of the outer bottom wall portion 34A, and the height of the narrowed portion 34G is set to 3 mm.

Further, in the third embodiment, the lower flange portion 32D2 of the first embodiment is omitted from the first flange 32D of the inner container 32, as in the second embodiment. Then, the first flange 32D (upper flange portion 32D1) of the inner container 32 and the second flange 34D of the outer container 34 are arranged so as to overlap vertically, and the tip of the first flange 32D and the second flange 34D of the outer container 34 The tip of the flange 34D is joined by laser welding or the like. Also, overlapping portions of the first flange 32D and the second flange 34D are joined by spot welding or the like.

Also in the third embodiment, when the bottom portion of the inner pot 100 is heated, the working fluid 40 injected into the closed space 36 is heated, and the phase change cycle in the working fluid 40 is repeated. As a result, in the inner pot 100 of the third embodiment, similarly to the first embodiment, the inner side wall portion 32B of the inner pot 100 is efficiently heated, and the entire inner pot 100 is heated substantially uniformly. can do.

Further, in the third embodiment, an upwardly raised narrowed portion 32G is formed in the inner bottom wall portion 32A, and an upwardly raised narrowed portion 34G is formed in the outer bottom wall portion 34A. Therefore, the narrowed portion 32G (thickened portion 34G) functions as a reinforcing narrowed portion for the inner bottom wall portion 32A (outer bottom wall portion 34A). As a result, even if the internal pressure of the sealed space 36 rises when the bottom of the inner pot 100 is heated, the inner bottom wall 32A and the outer bottom wall 34A can be prevented from flexing (deforming).

Regarding this point, the amount of vertical deflection (deformation) of the inner bottom wall portion 32A and the outer bottom wall portion 34A when the internal pressure in the closed space 36 is set to 5 atm, which is assumed to be the maximum pressure during heating, will be described below. will be used for explanation. That is, in a pot in which the throttle portion 32G and the throttle portion 34G are omitted from the inner bottom wall portion 32A and the outer bottom wall portion 34A, when the internal pressure in the sealed space 36 is set to 5 atm, the inner bottom wall portion 32A and the outer bottom wall portion 32A and the outer bottom wall portion It was found that the vertical deflection (deformation) amount of 34A was 2.4 mm. On the other hand, when the internal pressure in the sealed space 36 in the kettle 100 of the third embodiment is set to 5 atm, the vertical deflection (deformation) amount of the inner bottom wall portion 32A and the outer bottom wall portion 34A is 0.5 atm. It was confirmed to be 3 mm. Thereby, according to the inner pot 100 of the third embodiment, it is possible to suppress the bending (deformation) of the inner bottom wall portion 32A and the outer bottom wall portion 34A when the bottom portion is heated.

Further, in the third embodiment, as compared with the first embodiment, the connecting pin 42 is omitted. Flexure (deformation) of the outer bottom wall portion 34A can be suppressed.

(Regarding variations of the pipe 38)
In the following, variations of the pipe 38 used in the inner pots 30, 60, 90, 100 of the first embodiment (including modifications) to the third embodiment will be described with respect to the inner pot 90 of the second embodiment. will be used to explain.

(Regarding Variation 1 of Pipe 38)
As shown in FIGS. 14A and 14B, in variation 1 of the pipe 38 , the inner pot 90 is provided with a plurality of (two in this variation 1) pipes 38 . One of the two pipes 38 is configured as a pipe for injecting the hydraulic fluid 40 into the closed space 36 , and the other pipe 38 is configured as a pipe for vacuuming the closed space 36 . That is, in Variation 1, the pipes 38 are provided for each manufacturing process of the inner pot 90 (the process of injecting the working fluid 40 and the process of vacuuming). As a result, the process of injecting the working fluid 40 into the closed space 36 and the process of vacuuming the closed space 36 can be made more efficient.

In variation 1, the two pipes 38 are arranged at equal intervals (180 degrees apart) in the circumferential direction of the inner pot 90 . That is, the two pipes 38 are arranged to face each other in the radial direction of the inner pot 90 . Further, as a cover for variation 1 of the pipes 38, instead of the cover 50, a pair of pipe covers 110 covering only the respective pipes 38 are provided on the inner hook 90. As shown in FIG. The pipe cover 110 is formed in a substantially rectangular plate shape whose thickness direction is the vertical direction. Further, the pipe cover 110 is formed with a recess 110A that opens radially inward of the inner pot 90, and the recess 110A is formed in a circular shape when viewed from the radial direction of the inner pot. The pipe cover 110 is attached to the inner hook 90 by fitting the pipe 38 into the recess 110A. As a result, the pipe cover 110 that covers the pipe 38 can be used as the handle of the inner hook 90, and the pipe 38 can be used as the attachment portion (core portion) of the handle (pipe cover 110). By arranging the two pipes 38 at equal intervals in the circumferential direction of the inner pot 90 as described above, the pipe cover 110 as a handle can be arranged in a well-balanced manner. Therefore, the ease of holding the inner hook 90 can be improved, and the convenience for the user can be improved.

Although two pipes 38 are provided in the inner pot 90 in variation 1, three or more pipes 38 may be provided in the inner pot 90 . Also, in this case, the number of pipes 38 provided in the inner pot 90 may be set in consideration of the work time using the pipes 38 (work time for pouring the hydraulic fluid 40 and work time for vacuuming). . For example, if the work time for vacuuming is longer than the time for injecting the working fluid 40, the number of pipes 38 for vacuuming may be greater than the number of pipes 38 for injecting the working fluid 40. . As an example, one pipe 38 may be used for injecting the hydraulic fluid 40, and two pipes 38 may be used for evacuation. As a result, the working time using the pipe 38 can be shortened, and the manufacturing time of the inner pot 90 can be shortened.

Also, in variation 1, the diameters of the plurality of pipes 38 are set to be the same, but the diameters of the plurality of pipes 38 may be set to different dimensions. In this case, the diameter of the pipe 38 provided in the inner pot 90 may be changed in consideration of the work time using the pipe 38, as described above. For example, if the working time for vacuuming is longer than the time for injecting the working fluid 40, the diameter of the pipe 38 for vacuuming is made larger than the diameter of the pipe 38 for injecting the working fluid 40. good too. As a result, it is possible to shorten the working time in the same manner as described above.

Further, in variation 1, the plurality of (two) pipes 38 are arranged 180 degrees apart in the circumferential direction of the inner pot 90, but the positions of the plurality of pipes 38 in the circumferential direction of the inner pot 90 are , can be set arbitrarily. For example, a plurality of pipes 38 may be arranged adjacent to each other in the circumferential direction of the inner pot 90 . As a result, for example, it is possible to make the work space compact when connecting the tubes for hydraulic fluid injection and evacuation to the pipe 38 . Further, for example, it is possible to suppress the work of routing the tubes connected to the respective pipes 38, etc., and it is possible to contribute to the reduction of the manufacturing man-hours of the inner pot 90.

(Regarding Variation 2 of Pipe 38)
Variation 2 is configured in the same manner as Variation 1 above, except for the following points.
That is, as shown in FIG. 15, in variation 2, the pipe 38 is provided in the inner container 32 . Specifically, the pipe 38 extends (protrudes) radially inward of the inner hook 90 from the inner side wall portion 32B of the inner container 32 . A communication hole is formed in the inner side wall portion 32B so that the inside of the pipe 38 and the inside of the sealed space 36 communicate with each other. Accordingly, in Variation 2, the pipe 38 does not protrude radially outward of the inner hook 90 , so that deterioration of the appearance of the inner hook 90 can be suppressed. In addition, since the pipe 38 does not protrude radially outward of the inner pot 90, the inner pot 90 can be easily applied to existing rice cookers. Therefore, the versatility of the inner hook 90 can be improved. Note that, in variation 2 as well, a plurality of pipes 38 may be provided in the inner container 32 as in variation 1.

In variation 2, the vertical position of the pipe 38 is set so that the pipe 38 is positioned above the cooked rice (the maximum amount of rice cooked in the inner pot 90). Therefore, even if the pipe 38 is provided on the inner side wall portion 32B of the inner container 32, contact between the cooked rice and the pipe 38 can be suppressed.

In the inner pots 30, 60, 90, 100 of the first embodiment (including modifications) to the third embodiment, water is used as the hydraulic fluid 40. The type of hydraulic fluid 40 to be injected is not limited to this. For example, the hydraulic fluid 40 may be ethylene glycol, silicone oil, propylene glycol, or the like.

Further, in the first to third embodiments, the height dimension H of the bottom portion 36A of the closed space 36 is set to 4 mm. From the viewpoint of increasing the capacity of the pot 30, it is conceivable to lower the inner bottom wall portion 32A to make the height dimension H smaller. When the height dimension H is made lower (eg, 3 mm or less), the volume ratio of the hydraulic fluid 40 to the bottom portion 36A of the closed space 36 is 10 vol% to 80 vol%, particularly 30 vol% to 80 vol%. It is preferable to set
On the other hand, in order to heat the inner side wall portion 32B of the inner pot 30 more effectively, when the height dimension H is made higher than 4 mm in the present embodiment, the working fluid 40 does not flow into the bottom portion 36A of the closed space 36. It is preferable to set the volume ratio to 5 vol% to 80 vol%, particularly 8 vol% to 30 vol%.

Further, in the inner pots 30, 60, 90, 100 of the first embodiment (including modifications) to the third embodiment, when the inner pots 30, 60, 90, 100 are heated, the closed space 36 Since the internal pressure increases, the inner pot 30, 60, 90, 100 may be provided with a safety mechanism for preventing an abnormal increase in the internal pressure of the closed space 36. This point will be described below using the inner hook 90 of the second embodiment in FIG.

As shown in FIGS. 16A and 16B, a notch 32H that constitutes a safety mechanism is formed in the inner peripheral surface of the inner corner portion 32C of the inner container 32. The notch 32H It is formed in a straight line along a direction perpendicular to the circumferential direction of the. The notch 32H is formed in a substantially V-shaped groove that opens radially inward of the inner container 32, and the portion of the inner container 32 where the notch 32H is formed is the thin portion 32I (broadly speaking, the “weak portion”). ”). Therefore, the strength of the thin portion 32I of the inner container 32 is lower than that of other portions.

The shape (depth and width) of the notch 32H is set so that the thin portion 32I breaks when the internal pressure of the closed space 36 exceeds a predetermined value. As a result, when the internal pressure of the sealed space 36 exceeds a predetermined value during heating of the inner pot 90, the thin portion 32I is broken, and the steam in the sealed space 36 flows from the broken portion to the lower portion of the inner pot 90 (more specifically, is jetted to the part where the rice is placed). Therefore, the steam can escape from the steam tower in the lid portion 24 of the rice cooker 10 via the opening of the inner pot 90 . Therefore, an abnormal rise in the internal pressure of the closed space 36 can be suppressed, and the safety of the rice cooker 10 can be improved.

In the example shown in FIGS. 16A and 16B, the notch 32H extends linearly along the direction perpendicular to the circumferential direction of the inner hook 90. The existing direction can be set arbitrarily. For example, the notches 32H may be formed so as to extend in the circumferential direction of the inner pot 90 or may be formed so as to extend obliquely with respect to the circumferential direction of the inner pot 90 .
Also, in the example shown in FIGS. 16A and 16B, one notch 32H is formed in the inner hook 90, but the number of notches 32H may be plural.
Furthermore, in the examples shown in FIGS. 16A and 16B, the cross-sectional shape of the notch 32H is formed in a substantially V-shaped groove shape, but the cross-sectional shape of the notch 32H can be changed as appropriate. For example, the cross-sectional shape of the notch 32H may be formed in a substantially semicircular groove shape.

Further, in the above safety mechanism, the thin portion 32I is formed in the inner container 32, but the place where the thin portion 32I is formed can be set arbitrarily.
For example, a notch 32H may be formed in the pipe 38 to form a thinned portion 32I in the pipe 38 . That is, as shown in FIG. 16(C), one or more (two in the example shown in FIG. 16(C)) notches 32H are formed in the outer peripheral portion of the pipe 38 to make the pipe 38 thin. A portion 32I may be formed.
Further, for example, the thin portion 32I may be formed in the upper portion of the inner side wall portion 32B (preferably, a position above the maximum amount of rice cooked in the inner pot 90). In this case, the thin portion 32I is arranged at a position spaced apart from the bottom portion of the inner pot 90 (that is, the portion heated in the inner pot 90). Thereby, deterioration of the thin portion 32I can be suppressed. In particular, by arranging the thin portion 32I above the maximum amount of rice cooked in the inner pot 90, contact with the thin portion 32I after cooking can be suppressed.

In the above safety mechanism, the thin portion 32I is formed in the inner container 32 (inner side wall portion 32B), but the thin portion 32I is formed in the outer container 34 (outer side wall portion 34B) instead of the inner container 32. You may Also, the thin portion 32I may be formed in the inner container 32 and the outer container 34 . When the thin portions 32I are formed in the inner container 32 and the outer container 34, for example, when the internal pressure of the closed space 36 rises abnormally, even if one thin portion 32I does not break, the other thin portions 32I will not break. By breaking the thin wall portion 32I, the steam can escape to the outside of the closed space 36. Thereby, the safety of the rice cooker 10 can be further improved.

From the viewpoint of forming the thin portion 32I by reducing the plate thickness of the inner container 32, a portion of the inner container 32 (the inner side wall portion 32B) is crushed during press working of the inner container 32 to form the thin portion. 32I may be formed. For example, although illustration is omitted, a circular recess that is crushed inward in the plate thickness direction is formed in the inner peripheral surface or the outer peripheral surface of the inner side wall portion 32B, and the portion in which the recess is formed is the thin portion 32I. may be
Further, when the inner container 32 is pressed, part of the inner container 32 (the inner side wall portion 32B) may be half-blanked to form the thin portion 32I. For example, although not shown, a portion of the inner side wall portion 32B may be half punched radially inward or radially outward, and the boundary portion of the half punched portion may be the thin portion 32I.
As a result, the thin portion 32I can be easily formed, and the inner hook 90 can be manufactured at low cost. As in the above description, the concave portion and the half-cut portion may be formed in at least one of the inner container 32 and the outer container 34, and the positions of the concave portion and the half-cut portion can be set arbitrarily.

In addition, from the viewpoint of releasing steam to the outside of the sealed space 36 when the internal pressure of the sealed space 36 rises abnormally, the inner container 32 or the outer container 34 is provided with a safety valve (for example, a spring-type safety valve). may In this case, steam can escape to the outside of the sealed space 36 without destroying the inner pot 90 when the internal pressure of the sealed space 36 abnormally increases.

Further, in the first embodiment, the connecting pin 42 is provided in the inner pot 30, and the connecting pin 42 connects the inner bottom wall portion 32A and the outer bottom wall portion 34A. Alternatively, as shown in FIG. 17, in the inner hook 30, the connecting pin 42 (the center pin 44 and the outer peripheral pin 46) is omitted so that the inner bottom wall portion 32A and the outer bottom wall portion 34A are not connected. may

Further, although illustration is omitted, in the inner pots 30, 60, 90, 100 of the first embodiment (including modifications) to the third embodiment, the inner side wall portion 32B of the inner container 32 and the outer side wall portion 32B A connecting pin 42 may be provided between the outer side wall portion 34B of the container 34 and the inner side wall portion 32B and the outer side wall portion 34B may be connected by the connecting pin 42 . In this case, the connecting pin 42 is arranged with the radial direction of the inner hooks 30, 60, 90, 100 as the axial direction, and the connecting pin 42 connects the inner side wall portion 32B and the outer side wall portion 34B. Thereby, deformation of the inner side wall portion 32B and the outer side wall portion 34B during heating of the inner pots 30, 60, 90, 100 can be suppressed.

Furthermore, in this case, a plurality of connecting pins 42 are provided between the inner side wall portion 32B of the inner container 32 and the outer side wall portion 34B of the outer container 34, and the inner hooks 30, 60, 90, 100 may be arranged at regular intervals. As a result, while suppressing deformation of the inner side wall portion 32B and the outer side wall portion 34B during heating of the inner pot 30, 60, 90, 100, the gap between the inner side wall portion 32B and the outer side wall portion 34B in the closed space 36 is reduced. can be made uniform. As a result, in the circumferential direction of the inner pots 30, 60, 90, 100, variations in the amount of steam rising between the inner side wall portion 32B and the outer side wall portion 34B can be suppressed. Therefore, the inner side wall portion 32B can be evenly heated in the circumferential direction of the inner container 32 .

Further, in the first embodiment (including modifications) to the third embodiment, the inner hooks 30, 60, 90, 100 are configured including the cover 50, but the inner hooks 30, 60 , 90 and 100, the cover 50 may be omitted.
Further, the cover 50 of the first embodiment (including modifications) to the third embodiment includes a portion that covers the first flange 32D and the second flange 34D of the inner hook 30, 60, 90, 100, Both the portion covering the pipe 38 and the portion covering the pipe 38 are formed in a ring shape. Instead of this, the cover 50 is integrated with a ring-shaped portion that covers the entire circumference of the first flange 32D and the second flange 34D and a portion that covers only the pipe 38 (that is, the pipe cover 110 described above). It may be formed into a shape. Even in this case, the welded portions of the first flange 32D and the second flange 34D and the pipe 38 can be covered invisibly.

In addition, in the inner pot 30 (60) of the first embodiment (including the modification), the first flange 32D of the inner container 32 is aligned with the second flange of the outer container 34 at the opening of the inner pot 30 (60). The airtightness of the sealed space 36 is secured by folding back so as to wrap around 34D, but the structure for securing the airtightness of the sealed space 36 is not limited to this.
For example, as shown in FIG. 18, the second flange 34D is formed to be folded 180 degrees radially inward of the inner hooks 30, 60, and the first flange 32D of the inner container 32 is folded back into the second flange. It may be configured to wrap around 34D. That is, in this case, the second flange 34D forms a superimposed structure in which the second flanges 34D are superimposed one on top of the other. Further, the upper flange portion 32D1 and the lower flange portion 32D2 of the first flange 32D press the second flange 34D, which forms a superposed structure, vertically. As a result, the rigidity of the opening of the inner pot 30 (60) can be increased while ensuring the airtightness of the closed space 36 .

Further, in the first embodiment (including modifications) to the third embodiment, the inner peripheral surface of the inner container 32 is treated with Teflon. It is not limited to this. For example, all or part of the inner peripheral surface of the inner container 32 (for example, only the inner bottom wall portion 32A or only the inner side wall portion 32B) is roughened to make the inner peripheral surface of the inner container 32 uneven. can be formed to For example, the inner peripheral surface of the inner container 32 may be diamond-coated. Further, for example, the inner peripheral surface of the inner container 32 may be sandblasted, and after the sandblasting, Teflon processing may be performed. As a result, unevenness is formed on the inner peripheral surface of the inner container 32 . For this reason, relatively fine air bubbles are generated in the inner pot due to the unevenness when the rice is cooked. As a result, the rice in the inner pot can be uniformly heated by the generation of the air bubbles.

In addition, in the first embodiment (including modifications) to the third embodiment, the outer surface of the inner container 32 and the outer container 34 were The inner surface is mirror-finished, but from the viewpoint of facilitating the generation of steam in the closed space 36 during heating of the inner pot, the outer surface of the inner container 32 and the inner surface of the outer container 34 are roughened. may be applied. For example, the outer surface of the inner container 32 and the inner surface of the outer container 34 may be sandblasted to form the outer surface of the inner container 32 and the inner surface of the outer container 34 in an uneven shape.

Further, in the inner pots 30, 60, 90, and 100 of the first embodiment (including modifications) to the third embodiment, the plate thickness of the inner container 32 and the plate thickness of the outer container 34 are the same. Although set, the plate thickness of the inner container 32 and the plate thickness of the outer container 34 may be set to different plate thicknesses. For example, the plate thickness of the inner container 32 may be set thinner than the plate thickness of the outer container 34 so as to accelerate the heating of the inner container 32 . In addition, by setting the plate thickness of the inner container 32 to be thinner than the plate thickness of the outer container 34, the heat of the steam vaporized from the working fluid 40 in the closed space 36 is transferred to the inner pots 30, 60, 90, 100 Heat can be efficiently radiated to the inside of the inner pot 30, 60, 90, 100 at the inner side wall portion 32B.

Further, in the first embodiment (including modifications) to the third embodiment, the plate thicknesses of the inner container 32 and the outer container 34 are set to be uniform (constant) as a whole, but the inner container 32 And the plate thickness of the outer container 34 may be set unevenly. For example, in the inner container 32, the plate thickness of the inner side wall portion 32B may be set thinner than the plate thickness of the inner bottom wall portion 32A so as to promote heating of the inner side wall portion 32B. In this case, the plate thickness of the inner corner portion 32C of the inner container 32 may be set so as to decrease from the inner bottom wall portion 32A toward the inner side wall portion 32B.

In addition, in the first embodiment (including modifications) to the third embodiment, the inner container 32 and the outer container 34 are made of a magnetic material (stainless steel). Alternatively, the inner container 32 may be made of a high thermal conductor such as copper or aluminum. Also in this case, the inner container 32 can be efficiently heated when the inner pots 30, 60, 90, 100 are heated.
Alternatively, the inner container 32 may be molded using a pre-coated steel plate or the like whose surface is pre-coated with a fluororesin. As a result, the manufacturing process of the inner pots 30, 60, 90, 100 can be shortened.

Further, in the first embodiment (including modifications) to the third embodiment, the inner pot 30, 60, 90, 100 is applied to the IH rice cooker 10. Rice cookers to which 60, 90 and 100 are applied are not limited to these. For example, the heating unit 16 of the rice cooker 10 may be replaced with a heater, and the inner pots 30, 60, 90, 100 may be heated by the heater.

(Appendix)
As described above, the present invention has been described from the viewpoint of efficiently heating the inner side wall of the heating cooker having a double-wall structure having an enclosed space inside. can catch.

That is, in the heating cooker described in the background art, the working fluid is injected into the closed space, and when the bottom part of the heating cooker is heated, the working fluid boils, and the steam vaporized from the working fluid is released into the closed space side. Ascend to the department. As a result, the side walls inside the heating cooker are heated by the steam. Furthermore, the steam that has heated the side wall is condensed and changed into a liquid as the working liquid, and the liquid-changing working liquid descends by its own weight and returns to the bottom of the sealed space. The side portion of the heating cooker is heated by repeating the phase change cycle in the working fluid.
However, the above heat cooker has room for improvement in the following points. That is, in the heating cooker, as described above, when the bottom portion of the heating cooker is heated, steam vaporized from the working liquid rises to the side of the sealed space. By continuing to heat the heating cooker, the atmospheric pressure (pressure) in the sealed space rises. As a result, the bottom portion of the closed space expands, possibly deforming the bottom portion of the heating cooker. Therefore, it is desirable that a heating cooker having an enclosed space inside has a structure capable of suppressing deformation due to expansion of the heating cooker.
An object of the present invention is to provide a heating cooker capable of suppressing expansion during heating in consideration of the above facts.

A first aspect for solving the above problems is
A heating cooker having a double-walled structure formed in a cylindrical shape with a bottom and having a closed space inside,
a cylindrical inner container with a bottom that constitutes the inner portion of the heating cooker;
a cylindrical outer container with a bottom that constitutes the outer portion of the heating cooker;
a hydraulic fluid injected into the closed space;
a connecting portion provided in the closed space for connecting the inner bottom wall portion of the inner container and the outer bottom wall portion of the outer container;
Heating cooker with.

A second aspect for solving the above problems is
The heating cooker according to the first aspect, wherein the connecting portion is constituted by a connecting pin extending in the axial direction of the heating cooker.

A third aspect for solving the above problems is
The cooking device according to the second aspect, wherein the connecting pin is arranged at the center of the cooking device in a plan view seen from the opening side of the cooking device.

A fourth aspect for solving the above problems is
The heating cooker according to the first aspect, wherein the connecting portion radially extends from the center of the heating cooker in a plan view seen from the opening side of the heating cooker.

A fifth aspect for solving the above problems is
The heating cooker according to the fourth aspect, wherein a communication hole communicating with the sealed space partitioned by the connecting portion is formed in the lower end portion of the connecting portion.

30 Inner pot (cooker)
32 Inner container 32A Inner bottom wall 32B Inner side wall 32C Inner corner 32 Inner corner 34 Outer container 36 Sealed space 38 Pipe 36A Bottom 36B Bottom 40 Working fluid 60 Inner pot (cooker)
90 Inner pot (cooker)
100 Inner pot (cooker)
110 Pipe cover H Height dimension R at the bottom of the sealed space Radius W of the inner corner part Width dimension of the sealed space

Claims (7)

A heating cooker having a double-walled structure formed in a cylindrical shape with a bottom and having a closed space inside,
a cylindrical inner container with a bottom that constitutes the inner portion of the heating cooker;
a cylindrical outer container with a bottom that constitutes the outer portion of the heating cooker;
a hydraulic fluid injected into the closed space;
with
the amount of the hydraulic fluid in the closed space is set so as not to cover the entire bottom surface of the closed space ;
An inner corner portion is formed between the inner bottom wall portion and the inner side wall portion of the inner container, the inner corner portion being convexly curved to the outside of the inner container,
The heating cooker , wherein the radius of the inner corner portion is set to decrease from the inner bottom wall portion toward the inner side wall portion . 2. The heating cooker according to claim 1, wherein a volume ratio of said working fluid to a bottom portion of said closed space is set to 4 vol % to 80 vol %. 2. The height dimension of the sealed space at the bottom of the heating cooker is set to be equal to or greater than the width dimension of the sealed space at the side and 2 mm or more in longitudinal cross-sectional view. Item 2. The heating cooker according to Item 2. The heating cooker according to any one of claims 1 to 3, wherein the closed space is maintained at a reduced pressure or vacuum of 0.01 atm or less. The inner side wall of the inner container or the outer side wall of the outer container is provided with a plurality of pipes used when injecting the working fluid into the sealed space and when decompressing or evacuating the sealed space. 5. The heating cooker according to claim 4, characterized in that the heating cooker is 6. The cooking method according to claim 5, wherein a plurality of pipes are arranged at equal intervals in the circumferential direction of the heating cooker, and a pipe cover covering the pipes is attached to the pipes. vessel. The heating cooker according to any one of claims 1 to 6 , wherein the surfaces of the inner container and the outer container forming the closed space are mirror-finished.

Images